What Is Silver Nitrate?

Silver nitrate (AgNO₃)is a soluble chemical compound. Also known as lunar caustic, it has multiple scientific and practical uses in several industries. Although most people recognize the name from its former usage in hospitals, the compound is also used for cleaning solutions and to locate certain other chemicals.

When used in liquid drop form, silver nitrate can be used to identify certain other compounds such as iodine, chloride, and bromide. Materials are treated with a special solution to separate or deactivate certain other ions that are present, and drops of AgNO₃ are added. If a specific compound is present, the material will change colors: white indicates the presence of chloride, cream indicates bromide, and yellow indicates iodine.

Silver nitrate was also routinely used in hospitals to drop into the eyes of newborns to prevent blindness or infection from a mother's gonorrhea. This worked well and drastically lowered the incidence of blindness thanks to its antibacterial properties, although there were some complications with its use. An incorrect dosage sometimes led to infant blindness in some very severe cases.

Other medical uses include using swabs dipped in this compound to heal oral ulcers. Solid versions have been used to remove tissues around stomas, surgical openings in the body. Podiatrists also use it on occasion to kill bacteria and other harmful cells within the nail bed. Sometimes, it is also used to coat catheters and other medical equipment to prevent infection.

Because of its antibacterial properties, silver nitrate has been used to purify and decontaminate water on Space Shuttles, as well as in home filtration units. It has also been used to disinfect and clean vegetables, chicken farms, and in household cleaning products, such as laundry detergent. When used for these purposes, it is important that the substance is heavily diluted and used only as directed.

In some areas, silver nitrate has been used as an alternative to antibiotics. This is not recommended by the United States Food and Drug Administration (FDA), as using the compound incorrectly could be harmful. Although generally not dangerous when heavily diluted and used properly, it can be extremely corrosive and toxic when consumed or used in high enough levels. It can also cause burns if it is no handled with caution.